How Do I Properly Make ASM Codes for the Gamecube (Gecko)

I decided to get into ASM Coding for the Gamecube. I learned a good amount of ARM to work with the Nintendo Switch and I found the functions that are equivalent to what I want to do in PPC. I think I know enough PPC to do what I want to do. So, I used Dolphin Debugger to find the function that stores HP in Pokemon Colosseum. The address of the function is at 8011DC74 and the function is sth r4, 0x008A (r3). The address in question stores a 16-bit value, so it makes since Store Halfword is the function used. Furthermore, I know this is the proper function, as NOP'ing it prevents HP from being updated and this is the address I found by setting a breakpoint on write on the HP address.

I know r4 is what's being stored and I know 0x008A (r3) is where the value is being stored, that is, the current HP address.
I believe this assembler code would accomplish what I want:

li r4, 0
sth r4, 0x008A (r3)

My goal is to make r4 0 to set the HP value to 0 in order to make a one-hit kill code.

Using ASMWiiRD, I get the following code:
C211DC74 00000002
38800000 B083008A
60000000 00000000

I'm also under the assumption the code handler makes a branch to this function and sets a nop and a blr at the end, allowing the function to be passed back to the game.  

Problem is this prevents the game from starting. Dolphin says IntCPU = 00000000 at PC = 800018a8 last_PC = 812fffc8 LR = 80002ffc, with several similar areas incrementing the PC addresses after this. I know a one-hit kill code exists already, but I wanted to do something easy to get started with this type of coding. What am I doing wrong and how would I go about doing what I need to do? I already tried placing a blr into the assembler to see if that'd help (if the code handler didn't do it automatically as expected, but that didn't fix anything).

I tried the code on an actual Wii and it worked perfectly. Turns out, Dolphin just didn't like my code for whatever reason. I even got have it so it can be toggled off and on! I mean, the code already exists in the form of setting the opponent's HP to 0, but it does it by setting an address and not a function. So, this was at least fruitful as a lesson.

Dolphin isn't all that good as it should be for code creation of any kind, be it ASM or RAM Writes or even just poking. You're much better off, if you are to make ASM codes, to use Gecko dotNET and an actual Wii. Glad you got it working!

I have an actual Wii, as said above. Only problem is finding a USB Gecko or Shuriken USB (USB Gecko Clone). Haven't seen anyone selling them and no one produces either anymore. I guess from now on just use Dolphin to find functions associated with addresses and test my ASM codes on the Wii.

Oh, I know, I was just making a point, lol If you're really good with programming and electronics, tinkering with stuff, etc., the resources for building one can be found online. You just have to put everything together. A couple years ago, I was going to attempt it, but I can't program worth a shit and I know the bare minimum when it comes to electronics, but I can tinker with things... Provided I have the right tools. ... I didn't bother with it, because I knew I wouldn't / couldn't go all the way through with it.